> Note that it’s legal to sell stockfish as long as you’re compliant with GPLv3. ChessBase seems to be compliant.
Unless your license has been terminated by the copyright holders, in which case you cannot be compliant with the license because don't have a license to distribute the material at all.
> Stockfish argues that ChessBase isn’t compliant because they refuse to release the weights.
I haven't seen them argue this anywhere. You've linked to their previous statement in which they only say that they "condemn" the fact that the weights are not being released.
The announcement says that they've filed the lawsuit "to enforce the consequences of the license termination" because "ChessBase is ignoring the fact that they no longer have the right to distribute Stockfish, modified or unmodified, as part of their products."
> But GPLv3 doesn’t give you the ability to terminate a license arbitrarily; it requires you meet some specific criteria, and it’s unclear that ChessBase meets it.
"Moreover, your license from a particular copyright holder is reinstated permanently if the copyright holder notifies you of the violation by some reasonable means, this is the first time you have received notice of violation of this License (for any work) from that copyright holder, and you cure the violation prior to 30 days after your receipt of the notice."
Unless your license has been terminated by the copyright holders, in which case you cannot be compliant with the license because don't have a license to distribute the material at all.
> Stockfish argues that ChessBase isn’t compliant because they refuse to release the weights.
I haven't seen them argue this anywhere. You've linked to their previous statement in which they only say that they "condemn" the fact that the weights are not being released.
The announcement says that they've filed the lawsuit "to enforce the consequences of the license termination" because "ChessBase is ignoring the fact that they no longer have the right to distribute Stockfish, modified or unmodified, as part of their products."
> But GPLv3 doesn’t give you the ability to terminate a license arbitrarily; it requires you meet some specific criteria, and it’s unclear that ChessBase meets it.
You seem to be talking about this paragraph in the GPLv3 (https://github.com/official-stockfish/Stockfish/blob/sf_14/C...) :
"Moreover, your license from a particular copyright holder is reinstated permanently if the copyright holder notifies you of the violation by some reasonable means, this is the first time you have received notice of violation of this License (for any work) from that copyright holder, and you cure the violation prior to 30 days after your receipt of the notice."
However, this is not ChessBase's first violation. They've also tried to pass off Houdini as original work: https://shop.chessbase.com/en/products/houdini_6_pro_multipr...
Houdini 6 is also a stockfish clone. https://chess.stackexchange.com/questions/29181/is-houdini-6...